If the Wikipedia article is correct, video can be exported from Spark as H.264. (In what wrapper?) Then you'd wisely transcode to ProRes for FCP6/7 editing.
If you get a Spark thing as something other than H.264 video, maybe you can import it into Spark and then export as H.264 video.

That was my "(In what wrapper?)" question too.
While I share your satisfaction with OS 10.6.8, you could add a little volume with a newer OSX for occasional needs. It would have up-to-date QuickTime, more likely able to open funny new files, and able to output them as .mov. From the new volume send the .mov file back to the OS 10.6.8 volume.